<!doctype html>
<html>
<head>
<meta charset='UTF-8'><meta name='viewport' content='width=device-width initial-scale=1'>
<title>java01</title><link href='https://fonts.loli.net/css?family=PT+Serif:400,400italic,700,700italic&subset=latin,cyrillic-ext,cyrillic,latin-ext' rel='stylesheet' type='text/css' /><style type='text/css'>html {overflow-x: initial !important;}:root { --bg-color:#ffffff; --text-color:#333333; --select-text-bg-color:#B5D6FC; --select-text-font-color:auto; --monospace:"Lucida Console",Consolas,"Courier",monospace; }
html { font-size: 14px; background-color: var(--bg-color); color: var(--text-color); font-family: "Helvetica Neue", Helvetica, Arial, sans-serif; -webkit-font-smoothing: antialiased; }
body { margin: 0px; padding: 0px; height: auto; bottom: 0px; top: 0px; left: 0px; right: 0px; font-size: 1rem; line-height: 1.42857; overflow-x: hidden; background: inherit; }
iframe { margin: auto; }
a.url { word-break: break-all; }
a:active, a:hover { outline: 0px; }
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*, ::after, ::before { box-sizing: border-box; }
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sup.md-footnote { padding: 2px 4px; background-color: rgba(238, 238, 238, 0.7); color: rgb(85, 85, 85); border-radius: 4px; cursor: pointer; }
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thead { display: table-header-group; }
table { border-collapse: collapse; border-spacing: 0px; width: 100%; overflow: auto; break-inside: auto; text-align: left; }
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li div { padding-top: 0px; }
blockquote { margin: 1rem 0px; }
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li { margin: 0px; position: relative; }
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pre.md-meta-block { font-size: 0.8rem; min-height: 0.8rem; white-space: pre-wrap; background: rgb(204, 204, 204); display: block; overflow-x: hidden; }
p > .md-image:only-child:not(.md-img-error) img, p > img:only-child { display: block; margin: auto; }
p > .md-image:only-child { display: inline-block; width: 100%; }
#write .MathJax_Display { margin: 0.8em 0px 0px; }
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.md-toc-item { display: block; color: rgb(65, 131, 196); }
.md-toc-item a { text-decoration: none; }
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.md-toc-h2 .md-toc-inner { margin-left: 2em; }
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.md-toc-h6 .md-toc-inner { margin-left: 10em; }
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  .md-toc-h6 .md-toc-inner { margin-left: 8em; }
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code, pre, samp, tt { font-family: var(--monospace); }
kbd { margin: 0px 0.1em; padding: 0.1em 0.6em; font-size: 0.8em; color: rgb(36, 39, 41); background: rgb(255, 255, 255); border: 1px solid rgb(173, 179, 185); border-radius: 3px; box-shadow: rgba(12, 13, 14, 0.2) 0px 1px 0px, rgb(255, 255, 255) 0px 0px 0px 2px inset; white-space: nowrap; vertical-align: middle; }
.md-comment { color: rgb(162, 127, 3); opacity: 0.8; font-family: var(--monospace); }
code { text-align: left; vertical-align: initial; }
a.md-print-anchor { white-space: pre !important; border-width: initial !important; border-style: none !important; border-color: initial !important; display: inline-block !important; position: absolute !important; width: 1px !important; right: 0px !important; outline: 0px !important; background: 0px 0px !important; text-decoration: initial !important; text-shadow: initial !important; }
.md-inline-math .MathJax_SVG .noError { display: none !important; }
.html-for-mac .inline-math-svg .MathJax_SVG { vertical-align: 0.2px; }
.md-math-block .MathJax_SVG_Display { text-align: center; margin: 0px; position: relative; text-indent: 0px; max-width: none; max-height: none; min-height: 0px; min-width: 100%; width: auto; overflow-y: hidden; display: block !important; }
.MathJax_SVG_Display, .md-inline-math .MathJax_SVG_Display { width: auto; margin: inherit; display: inline-block !important; }
.MathJax_SVG .MJX-monospace { font-family: var(--monospace); }
.MathJax_SVG .MJX-sans-serif { font-family: sans-serif; }
.MathJax_SVG { display: inline; font-style: normal; font-weight: 400; line-height: normal; zoom: 90%; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; }
.MathJax_SVG * { transition: none; }
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[lang="mermaid"] svg, [lang="flow"] svg { max-width: 100%; }
[lang="mermaid"] .node text { font-size: 1rem; }
table tr th { border-bottom: 0px; }
video { max-width: 100%; display: block; margin: 0px auto; }
iframe { max-width: 100%; width: 100%; border: none; }
.highlight td, .highlight tr { border: 0px; }


.CodeMirror { height: auto; }
.CodeMirror.cm-s-inner { background: inherit; }
.CodeMirror-scroll { overflow-y: hidden; overflow-x: auto; z-index: 3; }
.CodeMirror-gutter-filler, .CodeMirror-scrollbar-filler { background-color: rgb(255, 255, 255); }
.CodeMirror-gutters { border-right: 1px solid rgb(221, 221, 221); background: inherit; white-space: nowrap; }
.CodeMirror-linenumber { padding: 0px 3px 0px 5px; text-align: right; color: rgb(153, 153, 153); }
.cm-s-inner .cm-keyword { color: rgb(119, 0, 136); }
.cm-s-inner .cm-atom, .cm-s-inner.cm-atom { color: rgb(34, 17, 153); }
.cm-s-inner .cm-number { color: rgb(17, 102, 68); }
.cm-s-inner .cm-def { color: rgb(0, 0, 255); }
.cm-s-inner .cm-variable { color: rgb(0, 0, 0); }
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.cm-s-inner .cm-string { color: rgb(170, 17, 17); }
.cm-s-inner .cm-property { color: rgb(0, 0, 0); }
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.cm-s-inner .cm-string-2 { color: rgb(255, 85, 0); }
.cm-s-inner .cm-meta { color: rgb(85, 85, 85); }
.cm-s-inner .cm-qualifier { color: rgb(85, 85, 85); }
.cm-s-inner .cm-builtin { color: rgb(51, 0, 170); }
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.cm-s-inner .cm-attribute { color: rgb(0, 0, 204); }
.cm-s-inner .cm-header, .cm-s-inner.cm-header { color: rgb(0, 0, 255); }
.cm-s-inner .cm-quote, .cm-s-inner.cm-quote { color: rgb(0, 153, 0); }
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.cm-invalidchar { color: red; }
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.cm-defined { color: rgb(181, 137, 0); }
div.CodeMirror span.CodeMirror-matchingbracket { color: rgb(0, 255, 0); }
div.CodeMirror span.CodeMirror-nonmatchingbracket { color: rgb(255, 34, 34); }
.cm-s-inner .CodeMirror-activeline-background { background: inherit; }
.CodeMirror { position: relative; overflow: hidden; }
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.CodeMirror-sizer { position: relative; }
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.CodeMirror-vscrollbar { right: 0px; top: 0px; overflow: hidden; }
.CodeMirror-hscrollbar { bottom: 0px; left: 0px; overflow: hidden; }
.CodeMirror-scrollbar-filler { right: 0px; bottom: 0px; }
.CodeMirror-gutter-filler { left: 0px; bottom: 0px; }
.CodeMirror-gutters { position: absolute; left: 0px; top: 0px; padding-bottom: 30px; z-index: 3; }
.CodeMirror-gutter { white-space: normal; height: 100%; box-sizing: content-box; padding-bottom: 30px; margin-bottom: -32px; display: inline-block; }
.CodeMirror-gutter-wrapper { position: absolute; z-index: 4; background: 0px 0px !important; border: none !important; }
.CodeMirror-gutter-background { position: absolute; top: 0px; bottom: 0px; z-index: 4; }
.CodeMirror-gutter-elt { position: absolute; cursor: default; z-index: 4; }
.CodeMirror-lines { cursor: text; }
.CodeMirror pre { border-radius: 0px; border-width: 0px; background: 0px 0px; font-family: inherit; font-size: inherit; margin: 0px; white-space: pre; word-wrap: normal; color: inherit; z-index: 2; position: relative; overflow: visible; }
.CodeMirror-wrap pre { word-wrap: break-word; white-space: pre-wrap; word-break: normal; }
.CodeMirror-code pre { border-right: 30px solid transparent; width: fit-content; }
.CodeMirror-wrap .CodeMirror-code pre { border-right: none; width: auto; }
.CodeMirror-linebackground { position: absolute; left: 0px; right: 0px; top: 0px; bottom: 0px; z-index: 0; }
.CodeMirror-linewidget { position: relative; z-index: 2; overflow: auto; }
.CodeMirror-wrap .CodeMirror-scroll { overflow-x: hidden; }
.CodeMirror-measure { position: absolute; width: 100%; height: 0px; overflow: hidden; visibility: hidden; }
.CodeMirror-measure pre { position: static; }
.CodeMirror div.CodeMirror-cursor { position: absolute; visibility: hidden; border-right: none; width: 0px; }
.CodeMirror div.CodeMirror-cursor { visibility: hidden; }
.CodeMirror-focused div.CodeMirror-cursor { visibility: inherit; }
.cm-searching { background: rgba(255, 255, 0, 0.4); }
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:root { --active-file-bg-color: rgba(32, 43, 51, 0.63); --active-file-text-color: white; --bg-color: #f3f2ee; --text-color: #1f0909; --control-text-color: #444; --rawblock-edit-panel-bd: #e5e5e5; --select-text-bg-color: rgba(32, 43, 51, 0.63); --select-text-font-color: white; }
pre { --select-text-bg-color: #36284e; --select-text-font-color: #fff; }
html { font-size: 16px; }
html, body { background-color: rgb(243, 242, 238); font-family: "PT Serif", "Times New Roman", Times, serif; color: rgb(31, 9, 9); line-height: 1.5em; }
#write { max-width: 40em; }
ol li { list-style-type: decimal; list-style-position: outside; }
ul li { list-style-type: disc; list-style-position: outside; }
ol, ul { list-style: none; }
blockquote, q { quotes: none; }
blockquote::before, blockquote::after, q::before, q::after { content: none; }
table { border-collapse: collapse; border-spacing: 0px; }
h1, h2, h3, h4, h5, h6 { font-weight: bold; }
h1 { font-size: 1.875em; line-height: 1.6em; margin-top: 2em; }
h2, h3 { font-size: 1.3125em; line-height: 1.15; margin-top: 2.28571em; margin-bottom: 1.15em; }
h3 { font-weight: normal; }
h4 { font-size: 1.125em; margin-top: 2.67em; }
h5, h6 { font-size: 1em; }
h1 { border-bottom: 1px solid; margin-bottom: 1.875em; padding-bottom: 0.8125em; }
a { text-decoration: none; color: rgb(6, 85, 136); }
a:hover, a:active { text-decoration: underline; }
p, blockquote, .md-fences { margin-bottom: 1.5em; }
h1, h2, h3, h4, h5, h6 { margin-bottom: 1.5em; }
blockquote { font-style: italic; border-left: 5px solid; margin-left: 2em; padding-left: 1em; }
ul, ol { margin: 0px 0px 1.5em 1.5em; }
.md-meta, .md-before, .md-after { color: rgb(153, 153, 153); }
table { margin-bottom: 1.5em; font-size: 1em; }
thead th, tfoot th { padding: 0.25em 0.25em 0.25em 0.4em; text-transform: uppercase; }
th { text-align: left; }
td { vertical-align: top; padding: 0.25em 0.25em 0.25em 0.4em; }
code, .md-fences { background-color: rgb(218, 218, 218); }
code { padding-left: 2px; padding-right: 2px; }
.md-fences { margin-left: 2em; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; }
pre, code, tt { font-size: 0.875em; line-height: 1.71429em; }
h1 { line-height: 1.3em; font-weight: normal; margin-bottom: 0.5em; }
p + ul, p + ol { margin-top: 0.5em; }
h3 + ul, h4 + ul, h5 + ul, h6 + ul, h3 + ol, h4 + ol, h5 + ol, h6 + ol { margin-top: 0.5em; }
li > ul, li > ol { margin-top: inherit; margin-bottom: 0px; }
li ol > li { list-style-type: lower-alpha; }
li li ol > li { list-style-type: lower-roman; }
h2, h3 { margin-bottom: 0.75em; }
hr { border-top: none; border-right: none; border-bottom: 1px solid; border-left: none; }
h1 { border-color: rgb(197, 197, 197); }
blockquote { border-color: rgb(186, 186, 186); color: rgb(101, 101, 101); }
blockquote ul, blockquote ol { margin-left: 0px; }
.ty-table-edit { background-color: transparent; }
thead { background-color: rgb(218, 218, 218); }
tr:nth-child(2n) { background: rgb(232, 231, 231); }
hr { border-color: rgb(197, 197, 197); }
.task-list { padding-left: 1rem; }
.md-task-list-item { padding-left: 1.5rem; list-style-type: none; }
.md-task-list-item > input::before { content: "√"; display: inline-block; width: 1.25rem; height: 1.6rem; vertical-align: middle; text-align: center; color: rgb(221, 221, 221); background-color: rgb(243, 242, 238); }
.md-task-list-item > input:checked::before, .md-task-list-item > input[checked]::before { color: inherit; }
#write pre.md-meta-block { min-height: 1.875rem; color: rgb(85, 85, 85); border: 0px; background: transparent; margin-left: 1em; margin-top: 1em; }
.md-image > .md-meta { color: rgb(155, 81, 70); }
.md-image > .md-meta { font-family: Menlo, "Ubuntu Mono", Consolas, "Courier New", "Microsoft Yahei", "Hiragino Sans GB", "WenQuanYi Micro Hei", serif; }
#write > h3.md-focus::before { left: -1.5rem; color: rgb(153, 153, 153); border-color: rgb(153, 153, 153); }
#write > h4.md-focus::before { left: -1.5rem; top: 0.25rem; color: rgb(153, 153, 153); border-color: rgb(153, 153, 153); }
#write > h5.md-focus::before { left: -1.5rem; color: rgb(153, 153, 153); border-color: rgb(153, 153, 153); }
#write > h6.md-focus::before { left: -1.5rem; top: 0.3125rem; color: rgb(153, 153, 153); border-color: rgb(153, 153, 153); }
.md-toc:focus .md-toc-content { margin-top: 19px; }
.md-toc-content:empty::before { color: rgb(6, 85, 136); }
.md-toc-item { color: rgb(6, 85, 136); }
#write div.md-toc-tooltip { background-color: rgb(243, 242, 238); }
#typora-sidebar { background-color: rgb(243, 242, 238); box-shadow: rgba(0, 0, 0, 0.376) 0px 6px 12px; }
.pin-outline #typora-sidebar { background: inherit; box-shadow: none; border-right: 1px dashed; }
.pin-outline #typora-sidebar:hover .outline-title-wrapper { border-left: 1px dashed; }
.outline-item:hover { background-color: rgb(218, 218, 218); border-left: 28px solid rgb(218, 218, 218); border-right: 18px solid rgb(218, 218, 218); }
.typora-node .outline-item:hover { border-right: 28px solid rgb(218, 218, 218); }
.outline-expander::before { content: ""; font-family: FontAwesome; font-size: 14px; top: 1px; }
.outline-expander:hover::before, .outline-item-open > .outline-item > .outline-expander::before { content: ""; }
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<div  id='write'  class = 'is-node'><div class='md-toc' mdtype='toc'><p class="md-toc-content"><span class="md-toc-item md-toc-h2" data-ref="n398"><a class="md-toc-inner" href="#header-n398">1:计算机概述(了解)</a></span><span class="md-toc-item md-toc-h4" data-ref="n399"><a class="md-toc-inner" href="#header-n399">(1)计算机</a></span><span class="md-toc-item md-toc-h4" data-ref="n400"><a class="md-toc-inner" href="#header-n400">(2)计算机硬件</a></span><span class="md-toc-item md-toc-h4" data-ref="n401"><a class="md-toc-inner" href="#header-n401">(3)计算机软件</a></span><span class="md-toc-item md-toc-h4" data-ref="n406"><a class="md-toc-inner" href="#header-n406">(4)软件开发(理解)</a></span><span class="md-toc-item md-toc-h4" data-ref="n414"><a class="md-toc-inner" href="#header-n414">(5)语言</a></span><span class="md-toc-item md-toc-h4" data-ref="n420"><a class="md-toc-inner" href="#header-n420">(6)人机交换</a></span><span class="md-toc-item md-toc-h2" data-ref="n427"><a class="md-toc-inner" href="#header-n427">2:键盘功能键的认识和快捷键(掌握)</a></span><span class="md-toc-item md-toc-h4" data-ref="n428"><a class="md-toc-inner" href="#header-n428">(1)功能键的认识</a></span><span class="md-toc-item md-toc-h4" data-ref="n447"><a class="md-toc-inner" href="#header-n447">(2)快捷键</a></span><span class="md-toc-item md-toc-h2" data-ref="n462"><a class="md-toc-inner" href="#header-n462">3:常见的DOS命令(掌握)</a></span><span class="md-toc-item md-toc-h4" data-ref="n463"><a class="md-toc-inner" href="#header-n463">(1)常见的如下</a></span><span class="md-toc-item md-toc-h4" data-ref="n475"><a class="md-toc-inner" href="#header-n475">(2)其他的几个(了解)</a></span><span class="md-toc-item md-toc-h2" data-ref="n489"><a class="md-toc-inner" href="#header-n489">4:Java语言概述(了解)</a></span><span class="md-toc-item md-toc-h4" data-ref="n490"><a class="md-toc-inner" href="#header-n490">(1)Java语言的发展史</a></span><span class="md-toc-item md-toc-h4" data-ref="n492"><a class="md-toc-inner" href="#header-n492">(2)Java语言的特点</a></span><span class="md-toc-item md-toc-h4" data-ref="n494"><a class="md-toc-inner" href="#header-n494">(3)Java语言是跨平台的，请问是如何保证的呢?(理解)</a></span><span class="md-toc-item md-toc-h4" data-ref="n496"><a class="md-toc-inner" href="#header-n496">(4)Java语言的平台</a></span><span class="md-toc-item md-toc-h2" data-ref="n498"><a class="md-toc-inner" href="#header-n498">5:JDK,JRE,JVM的作用及关系(掌握)</a></span><span class="md-toc-item md-toc-h4" data-ref="n499"><a class="md-toc-inner" href="#header-n499">(1)作用</a></span><span class="md-toc-item md-toc-h4" data-ref="n506"><a class="md-toc-inner" href="#header-n506">(2)关系</a></span><span class="md-toc-item md-toc-h2" data-ref="n513"><a class="md-toc-inner" href="#header-n513">6:JDK的下载,安装,卸载(掌握)</a></span><span class="md-toc-item md-toc-h4" data-ref="n514"><a class="md-toc-inner" href="#header-n514">(1)下载到官网。</a></span><span class="md-toc-item md-toc-h4" data-ref="n519"><a class="md-toc-inner" href="#header-n519">(2)安装</a></span><span class="md-toc-item md-toc-h4" data-ref="n527"><a class="md-toc-inner" href="#header-n527">(3)卸载</a></span><span class="md-toc-item md-toc-h2" data-ref="n539"><a class="md-toc-inner" href="#header-n539">7:第一个程序：HelloWorld案例(掌握)</a></span><span class="md-toc-item md-toc-h4" data-ref="n541"><a class="md-toc-inner" href="#header-n541">(1)程序解释：</a></span><span class="md-toc-item md-toc-h6" data-ref="n542"><a class="md-toc-inner" href="#header-n542">A:Java程序的最基本单位是类，所以我们要定义一个类。</a></span><span class="md-toc-item md-toc-h6" data-ref="n547"><a class="md-toc-inner" href="#header-n547">B:在类中写内容的时候，用大括号括起来。</a></span><span class="md-toc-item md-toc-h6" data-ref="n549"><a class="md-toc-inner" href="#header-n549">C:Java程序要想执行，必须有main方法。</a></span><span class="md-toc-item md-toc-h6" data-ref="n552"><a class="md-toc-inner" href="#header-n552">D:要指向那些东西呢，也用大括号括起来。</a></span><span class="md-toc-item md-toc-h6" data-ref="n554"><a class="md-toc-inner" href="#header-n554">E:你要做什么呢?今天我们仅仅做了一个简单的输出</a></span><span class="md-toc-item md-toc-h4" data-ref="n559"><a class="md-toc-inner" href="#header-n559">(2)Java程序的开发执行流程：</a></span><span class="md-toc-item md-toc-h6" data-ref="n563"><a class="md-toc-inner" href="#header-n563">A:编写java源程序(.java)</a></span><span class="md-toc-item md-toc-h6" data-ref="n565"><a class="md-toc-inner" href="#header-n565">B:通过javac命令编译生成.class文件</a></span><span class="md-toc-item md-toc-h6" data-ref="n567"><a class="md-toc-inner" href="#header-n567">C:通过java命令运行.class文件</a></span><span class="md-toc-item md-toc-h2" data-ref="n568"><a class="md-toc-inner" href="#header-n568">8:常见的问题(掌握)</a></span><span class="md-toc-item md-toc-h4" data-ref="n569"><a class="md-toc-inner" href="#header-n569">(1)扩展名被隐藏</a></span><span class="md-toc-item md-toc-h4" data-ref="n570"><a class="md-toc-inner" href="#header-n570">(2)我要求文件名称和类名一致。</a></span><span class="md-toc-item md-toc-h4" data-ref="n572"><a class="md-toc-inner" href="#header-n572">(3)Java语言严格区分大小写，请注意。</a></span><span class="md-toc-item md-toc-h4" data-ref="n574"><a class="md-toc-inner" href="#header-n574">(4)见到非法字符: \65307肯定是中文问题。</a></span><span class="md-toc-item md-toc-h4" data-ref="n576"><a class="md-toc-inner" href="#header-n576">(5)括号的配对问题。</a></span><span class="md-toc-item md-toc-h4" data-ref="n578"><a class="md-toc-inner" href="#header-n578">(6)遇到</a></span><span class="md-toc-item md-toc-h2" data-ref="n580"><a class="md-toc-inner" href="#header-n580">9:path环境变量(掌握)</a></span><span class="md-toc-item md-toc-h4" data-ref="n581"><a class="md-toc-inner" href="#header-n581">(1)path环境变量的作用</a></span><span class="md-toc-item md-toc-h4" data-ref="n583"><a class="md-toc-inner" href="#header-n583">(2)path配置的两种方案：</a></span><span class="md-toc-item md-toc-h2" data-ref="n585"><a class="md-toc-inner" href="#header-n585">10:classpath环境变量(理解)</a></span><span class="md-toc-item md-toc-h4" data-ref="n586"><a class="md-toc-inner" href="#header-n586">(1)classpath环境变量的作用</a></span><span class="md-toc-item md-toc-h4" data-ref="n588"><a class="md-toc-inner" href="#header-n588">(2)classpath环境变量的配置</a></span></p></div><h2><a name='header-n398' class='md-header-anchor '></a>1:计算机概述(了解)</h2><h4><a name='header-n399' class='md-header-anchor '></a>(1)计算机</h4><h4><a name='header-n400' class='md-header-anchor '></a>(2)计算机硬件</h4><h4><a name='header-n401' class='md-header-anchor '></a>(3)计算机软件</h4><ul><li>系统软件：window,linux,mac</li><li>应用软件：qq,yy,飞秋</li></ul><h4><a name='header-n406' class='md-header-anchor '></a>(4)软件开发(理解)</h4><ul><li>软件：是由数据和指令组成的。(计算器)</li><li>开发：就是把软件做出来。</li><li>如何实现软件开发呢?
就是使用开发工具和计算机语言做出东西来</li></ul><h4><a name='header-n414' class='md-header-anchor '></a>(5)语言</h4><ul><li>自然语言：人与人交流沟通的</li><li>计算机语言：人与计算机交流沟通的
C,C++,C#,Java</li></ul><h4><a name='header-n420' class='md-header-anchor '></a>(6)人机交换</h4><ul><li>图形界面：操作方便只管</li><li>DOS命令：需要记忆一些常见的命令</li></ul><h2><a name='header-n427' class='md-header-anchor '></a>2:键盘功能键的认识和快捷键(掌握)</h2><h4><a name='header-n428' class='md-header-anchor '></a>(1)功能键的认识</h4><ul><li>tab</li><li>shift</li><li>ctrl</li><li>alt</li><li>windos</li><li>空格</li><li>上下左右</li><li>回车</li><li>截图</li></ul><h4><a name='header-n447' class='md-header-anchor '></a>(2)快捷键</h4><ul><li>全选<span>	</span>Ctrl+A</li><li>复制<span>	</span>Ctrl+C</li><li>粘贴<span>	</span>Ctrl+V</li><li>剪切<span>	</span>Ctrl+X</li><li>撤销<span>	</span>Ctrl+Z</li><li>保存<span>	</span>Ctrl+S</li></ul><h2><a name='header-n462' class='md-header-anchor '></a>3:常见的DOS命令(掌握)</h2><h4><a name='header-n463' class='md-header-anchor '></a>(1)常见的如下</h4><ul><li>盘符的切换
<code>d:</code>回车</li><li>目录的进入
<code>cd javase</code>
<code>cd javase\day01\code</code></li><li>目录的回退
<code>cd..</code>
<code>cd\</code></li><li>清屏
<code>cls</code></li><li>退出
<code>exit</code></li></ul><h4><a name='header-n475' class='md-header-anchor '></a>(2)其他的几个(了解)</h4><ul><li>创建目录</li><li>删除目录</li><li>创建文件</li><li>删除文件</li><li>显示目录下的内容</li><li>删除带内容的目录</li></ul><h2><a name='header-n489' class='md-header-anchor '></a>4:Java语言概述(了解)</h2><h4><a name='header-n490' class='md-header-anchor '></a>(1)Java语言的发展史</h4><p>Java之父
JDK1.4.2
JDK5
JDK7</p><h4><a name='header-n492' class='md-header-anchor '></a>(2)Java语言的特点</h4><p>有很多小特点，重点有两个开源，跨平台</p><h4><a name='header-n494' class='md-header-anchor '></a>(3)Java语言是跨平台的，请问是如何保证的呢?(理解)</h4><p>我们是通过翻译的案例讲解的。
针对不同的操作系统，提高不同的jvm来实现的。</p><h4><a name='header-n496' class='md-header-anchor '></a>(4)Java语言的平台</h4><p>JavaSE
JavaME--Android
JavaEE</p><h2><a name='header-n498' class='md-header-anchor '></a>5:JDK,JRE,JVM的作用及关系(掌握)</h2><h4><a name='header-n499' class='md-header-anchor '></a>(1)作用</h4><ul><li>JVM：保证Java语言跨平台</li><li>JRE：Java程序的运行环境</li><li>JDK：Java程序的开发环境</li></ul><h4><a name='header-n506' class='md-header-anchor '></a>(2)关系</h4><ul><li>JDK：JRE+工具</li><li>JRE：JVM+类库</li></ul><h2><a name='header-n513' class='md-header-anchor '></a>6:JDK的下载,安装,卸载(掌握)</h2><h4><a name='header-n514' class='md-header-anchor '></a>(1)下载到官网。</h4><ul><li>A:也可以到百度搜索即可。</li><li>B:我给你。</li></ul><h4><a name='header-n519' class='md-header-anchor '></a>(2)安装</h4><ul><li>A:绿色版<span>	</span>解压就可以使用</li><li>B:安装版<span>	</span>必须一步一步的安装，一般只要会点击下一步即可</li><li>注意：
建议所有跟开发相关的软件都不要安装在有中文或者空格的目录下。</li></ul><h4><a name='header-n527' class='md-header-anchor '></a>(3)卸载</h4><ul><li><p>A:绿色版<span>	</span>直接删除文件夹</p></li><li><p>B:安装版<span>	</span></p><ul><li>a:控制面板 -- 添加删除程序</li><li>b:通过专业的软件卸载工具。(比如360的软件管家卸载)</li></ul></li></ul><h2><a name='header-n539' class='md-header-anchor '></a>7:第一个程序：HelloWorld案例(掌握)</h2><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="java"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 3.99999px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">class</span> <span class="cm-def">HelloWorld</span> {</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">public</span> <span class="cm-keyword">static</span> <span class="cm-variable-3">void</span> <span class="cm-variable">main</span>(<span class="cm-variable-3">String</span>[] <span class="cm-variable">args</span>) {</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-variable">System</span>.<span class="cm-variable">out</span>.<span class="cm-variable">println</span>(<span class="cm-string">"HelloWorld"</span>);</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp;  }</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;">}</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom: 0px solid transparent; top: 120px;"></div><div class="CodeMirror-gutters" style="display: none; height: 120px;"></div></div></div></pre><h4><a name='header-n541' class='md-header-anchor '></a>(1)程序解释：</h4><h6><a name='header-n542' class='md-header-anchor '></a>A:Java程序的最基本单位是类，所以我们要定义一个类。</h6><ul><li>格式：<code>class</code> 类名</li><li>举例：<code>class HelloWorld</code></li></ul><h6><a name='header-n547' class='md-header-anchor '></a>B:在类中写内容的时候，用大括号括起来。</h6><h6><a name='header-n549' class='md-header-anchor '></a>C:Java程序要想执行，必须有main方法。</h6><ul><li>格式：<code>public static void main(String[] args)</code></li></ul><h6><a name='header-n552' class='md-header-anchor '></a>D:要指向那些东西呢，也用大括号括起来。</h6><h6><a name='header-n554' class='md-header-anchor '></a>E:你要做什么呢?今天我们仅仅做了一个简单的输出</h6><ul><li>格式：<code>System.out.println(&quot;HelloWorld&quot;);</code></li><li>注意：&quot;&quot;里面的内容是可以改动的。</li></ul><h4><a name='header-n559' class='md-header-anchor '></a>(2)Java程序的开发执行流程：</h4><h6><a name='header-n563' class='md-header-anchor '></a>A:编写java源程序(.java)</h6><h6><a name='header-n565' class='md-header-anchor '></a>B:通过javac命令编译生成.class文件</h6><h6><a name='header-n567' class='md-header-anchor '></a>C:通过java命令运行.class文件</h6><h2><a name='header-n568' class='md-header-anchor '></a>8:常见的问题(掌握)</h2><h4><a name='header-n569' class='md-header-anchor '></a>(1)扩展名被隐藏</h4><p>如何找到：工具--文件夹选项--查看--去除隐藏扩展名的那个勾勾</p><h4><a name='header-n570' class='md-header-anchor '></a>(2)我要求文件名称和类名一致。</h4><p>实际上不这样做也是可以的。
但是，注意：
javac后面跟的是文件名+扩展名
java后面跟的类名不带扩展名</p><h4><a name='header-n572' class='md-header-anchor '></a>(3)Java语言严格区分大小写，请注意。</h4><p>还有就是单词不要写错了。</p><h4><a name='header-n574' class='md-header-anchor '></a>(4)见到非法字符: \65307肯定是中文问题。</h4><p>我们写程序要求标点符号必须全部是英文状态。</p><h4><a name='header-n576' class='md-header-anchor '></a>(5)括号的配对问题。</h4><p>一般来说，括号都是成对出现的。</p><h4><a name='header-n578' class='md-header-anchor '></a>(6)遇到</h4><p>在类 HelloWorld 中找不到主方法, 请将主方法定义为
肯定是主方法的格式问题。</p><h2><a name='header-n580' class='md-header-anchor '></a>9:path环境变量(掌握)</h2><h4><a name='header-n581' class='md-header-anchor '></a>(1)path环境变量的作用</h4><p>保证javac命令可以在任意目录下运行。
同理可以配置qq等</p><h4><a name='header-n583' class='md-header-anchor '></a>(2)path配置的两种方案：</h4><p>A:方案1(了解)
B:方案2
找到环境变量的位置，在系统变量里面
新建：
变量名：<code>JAVA_HOME</code>
变量值：<code>D:\develop\Java\jdk1.7.0_60</code>
修改：
变量名：<code>Path</code>
变量值：<code>%JAVA_HOME%\bin;</code>以前的内容</p><h2><a name='header-n585' class='md-header-anchor '></a>10:classpath环境变量(理解)</h2><h4><a name='header-n586' class='md-header-anchor '></a>(1)classpath环境变量的作用</h4><p>保证class文件可以在任意目录下运行</p><h4><a name='header-n588' class='md-header-anchor '></a>(2)classpath环境变量的配置</h4><p>找到环境变量的位置，在系统变量里面
新建：
变量名：<code>classpath</code>
变量值：<code>E:\JavaSE\day01\code\HelloWorld案例</code></p></div>
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